When applications attempt to open files in this directory, a remote connection
to the Cloud SQL instance of the same name will be established.

For example, when you run one of the following commands, the proxy will initiate
a connection to the corresponding Cloud SQL instance, given you have the correct
IAM permissions.

	mysql -u root -S "/somedir/project:region:instance"

    # or

	psql "host=/somedir/project:region:instance dbname=mydb user=myuser"

For MySQL, the proxy will create a socket with the instance connection name
(e.g., project:region:instance) in this directory. For Postgres, the proxy will
create a directory with the instance connection name, and create a socket inside
that directory with the special Postgres name: .s.PGSQL.5432.

Listing the contents of this directory will show all instances with active
connections.